Variator Multiplex Valve Scheme for a Torroidal Traction Drive Transmission

ABSTRACT

An apparatus and method are disclosed for controlling fluid flow to a variator which responsive to separate high and low pressure fluids to control an output torque thereof. A first trim valve may be responsive to a first control signal to supply a first fluid at a fluid outlet thereof. A second trim valve may be responsive to a second control signal to supply a second fluid at a fluid outlet thereof. A variator switching sub-system may controllably supply the high pressure fluid and the low pressure fluid to the variator. A multiplex valve may be fluidly coupled to the outlets of the first and second trim valves, and may supply the first fluid as the high pressure fluid to the variator switching sub-system during at least one predefined operating condition and may otherwise supply the second fluid as the high pressure fluid to the variator switching sub-system.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation application of U.S. patentapplication Ser. No. 13/325,355 entitled “VARIATOR MULTIPLEX VALVESCHEME FOR A TORROIDAL TRACTION DRIVE TRANSMISSION,” which was filed onDec. 14, 2011, and which claims priority under 35 U.S.C. §119(e) to U.S.Provisional Application Ser. No. 61/423,297, filed Dec. 15, 2010, eachof which is incorporated herein by reference.

TECHNICAL FIELD

The present invention relates generally to torroidal traction driveautomatic transmissions, and more specifically to systems and methodsfor controlling fluid flow to a variator during various transmissionoperating conditions.

BACKGROUND

Torroidal traction drive automatic transmissions may typically include avariator and one or more gear sets. Within each gear set, the variatormay generally control a direction, e.g., positive or negative, andmagnitude of torque transferred by a power plant to one or more loads.Structures and techniques for controlling fluid flow to the variatorduring various operating conditions of the transmission must thereforebe designed and implemented.

SUMMARY

The present application discloses one or more of the features recited inthe appended claims and/or the following features which alone or in anycombination, may comprise patentable subject matter.

An apparatus for controlling fluid flow to a variator in an automatictransmission. The variator may be responsive to separate high and lowpressure fluids to control an output torque of the variator. Theapparatus may comprise a first trim valve responsive to a first controlsignal to supply a first fluid at a fluid outlet thereof, a second trimvalve responsive to a second control signal to supply a second fluid ata fluid outlet thereof, a variator switching sub-system controllablysupplying the high pressure fluid and the low pressure fluid to thevariator, and a multiplex valve fluidly coupled to the outlets of thefirst and second trim valves, the multiplex valve supplying the firstfluid supplied by the first trim valve as the high pressure fluid to thevariator switching sub-system during at least one predefined operatingcondition of the automatic transmission and otherwise supplying thesecond fluid supplied by the second trim valve as the high pressurefluid to the variator switching sub-system.

The apparatus may further comprise a control circuit including a memoryhaving instructions stored therein executable by the control circuit toproduce the first and second control signals. The at least onepredefined operating condition may comprise at least one of a faultcondition associated with the automatic transmission and a cold startcondition.

The multiplex valve may comprise a spool having a stroked operatingstate and a destroked operating state. The multiplex valve may supplythe first fluid as the high pressure fluid to the variator switchingsub-system in one of the stroked operating state and the destrokedoperating state, and the multiplex valve may supply the second fluid asthe high pressure fluid to the variator switching sub-system in theother one of the stroked operating state and the destroked operatingstate. The apparatus may further comprise a control valve responsive toa third control signal to control the multiplex valve to the strokedoperating state and to a fourth control signal to control the multiplexvalve to the destroked operating state. The apparatus may furthercomprise a control circuit including a memory having instructions storedtherein executable by the control circuit to produce one of the thirdand fourth control signals to control the control valve to the other oneof the stroked operating state and the destroked operating state duringthe at least one predefined operating condition, and the at least onepredefined operating condition may comprise at least one of a faultcondition associated with the automatic transmission and a cold startcondition.

The apparatus may further comprise a regulator valve fluidly coupled bythe multiplex valve to a reference pressure during the at least onepredefined operating condition. The regulator valve may also be fluidlycoupled to a main fluid passageway that is further fluidly connected toa fluid inlet of the first trim valve. The regulator valve may beresponsive to the reference pressure to regulate fluid pressure in themain fluid passageway to a fixed pressure main fluid during the at leastone predefined operating condition. The fluid outlet of the first trimvalve may be fluidly coupled by the multiplex valve to the variatorswitching sub-system during the at least one predefined operatingcondition. The first trim valve may be responsive to the first controlsignal to supply the first fluid as the high pressure fluid based on thefixed pressure main fluid during the at least one predefined operatingcondition. The main fluid passageway may be further fluidly coupled bythe regulator valve to a fluid inlet of the second trim valve. Thesecond trim valve may be responsive to the second control signal tosupply the second fluid to the multiplex valve based on the fixedpressure main fluid during the at least one predefined operatingcondition. The multiplex valve may block the fixed pressure second fluidfrom the variator switching sub-system during the at least onepredefined operating condition. The variator may have at least oneroller between a first torroidal disk coupled to an input of theautomatic transmission and a second torroidal disk coupled to an outputof the automatic transmission. The variator may be fluidly coupled to anendload fluid passageway. The endload fluid passageway may definetherein an endload pressure corresponding to a pressure load on thefirst and second torroidal disks required to keep the first and secondtorroidal disks from slipping. The endload fluid passageway may befluidly coupled to the multiplex valve. The multiplex valve may fluidlycouple the endload fluid passageway to the main fluid passageway tothereby supply the fixed pressure main fluid to the endload fluidpassageway during the at least one predefined operating condition.

The apparatus may further comprise a control circuit including a memoryhaving instructions stored therein executable by the control circuit toproduce the other one of the third and fourth control signals to controlthe control valve to the one of the stroked operating state and thedestroked operating state during operating conditions other than the atleast one predefined operating condition.

The apparatus may further comprise a regulator valve fluidly coupled bythe multiplex valve to the fluid outlet of the first trim valve duringoperating conditions other than the at least one predefined operatingcondition. The regulator valve may also be fluidly coupled to a mainfluid passageway that is further fluidly connected to a fluid inlet ofthe first trim valve. The first trim valve may be responsive to thefirst control signal to supply the first fluid to the fluid outlet ofthe first trim valve based on pressure of fluid in the main fluidpassageway during the operating conditions other than the at least onepredefined operating condition. The regulator valve may be responsive tothe first fluid to regulate fluid pressure in the main fluid passagewayduring the operating conditions other than the at least one predefinedoperating condition. The main fluid passageway may be further fluidlycoupled by the regulator valve to a fluid inlet of the second trimvalve. The fluid outlet of the second trim valve may be fluidly coupledby the multiplex valve to the variator switching sub-system during theoperating conditions other than the at least one predefined operatingcondition. The second trim valve may be responsive to the second controlsignal to supply the second fluid as the high pressure fluid based onfluid pressure in the main fluid passageway during the conditions otherthan the at least one predefined operating condition. The variator mayhave at least one roller between a first torroidal disk coupled to aninput of the automatic transmission and a second torroidal disk coupledto an output of the automatic transmission. The variator may be fluidlycoupled to an endload fluid passageway. The endload fluid passageway maydefine therein an endload pressure corresponding to a pressure load onthe first and second torroidal disks required to keep the first andsecond torroidal disks from slipping. The endload fluid passageway maybe fluidly coupled to the multiplex valve. The multiplex valve mayfluidly couple the endload fluid passageway to a variable pressure fluidpassageway of the variator such that fluid pressure in the endload fluidpassageway is variably controlled by the variator during the operatingconditions other than the at least one predefined operating condition.

A method for controlling fluid flow to a variator in an automatictransmission, wherein the variator is responsive to separate high andlow pressure fluids supplied by a variator switching sub-system tocontrol an output torque of the variator, may comprise supplying a firstfluid supplied by a first trim valve as the high pressure fluid to thevariator switching sub-system during at least one predefined operatingcondition of the automatic transmission, and supplying a second fluidsupplied by a second trim valve separate from the first trim valve asthe high pressure fluid to the variator switching sub-system duringoperating conditions other than the at least one predefined operatingcondition.

The first fluid supplied by the first trim valve to the variatorswitching sub-system as the high pressure fluid during the at least onepredefined operating condition of the automatic transmission may be avariable pressure fluid. The variable pressure first fluid supplied bythe first trim valve to the variator switching sub-system as the highpressure fluid during the at least one predefined operating conditionmay be derived from a main fluid, and the method may further compriseregulating pressure of the main fluid to a fixed pressure based on afixed reference pressure during the at least one predefined operatingcondition.

The fixed reference pressure may be ambient pressure.

The second fluid supplied by the second trim valve to the variatorswitching sub-system as the high pressure fluid during the operatingconditions other than the at least one predefined operating condition ofthe automatic transmission may be a variable pressure fluid. Thevariable pressure second fluid supplied by the second trim valve to thevariator switching sub-system as the high pressure fluid during theoperating conditions other than the at least one predefined operatingcondition may be derived from a main fluid, and wherein the method mayfurther comprise modulating fluid pressure of the main fluid based onthe first fluid supplied by the first trim valve during the operatingcondition other than the at least one predefined operating condition.

The variator may have at least one roller between a first torroidal diskcoupled to an input of the automatic transmission and a second torroidaldisk coupled to an output of the automatic transmission, and thevariator may have an endload fluid passageway defining therein anendload pressure corresponding to a pressure load on the first andsecond torroidal disks required to keep the first and second torroidaldisks from slipping. The method may further comprise supplying a fixedpressure fluid to the endload fluid passageway during the at least onepredefined operating condition. The method may further comprise fluidlycoupling the endload fluid passageway to a variable pressure fluidpassageway of the variator during the operating conditions other thanthe at least one predefined operating condition such that fluid pressurein the endload fluid passageway is variably controlled by the variatorduring the operating conditions other than the at least one predefinedoperating condition.

The at least one predefined operating condition may comprise at leastone of a fault condition associated with the automatic transmission anda cold start condition.

Additional features and advantages of the invention will become apparentto those skilled in the art upon consideration of the following detaileddescription of illustrated embodiments exemplifying the best mode ofcarrying out the invention as presently perceived.

DESCRIPTION OF THE DRAWINGS

The systems and methods described herein are illustrated by way ofexample and not by way of limitation in the accompanying figures. Forsimplicity and clarity of illustration, elements illustrated in theFIGS. are not necessarily drawn to scale. For example, the dimensions ofsome elements may be exaggerated relative to other elements for clarity.Further, where considered appropriate, reference labels have beenrepeated among the FIGS. to indicate corresponding or analogouselements.

FIG. 1 is a block diagram of one illustrative embodiment of a system forcontrolling operation of a toroidal traction drive automatictransmission.

FIG. 2A is a diagram illustrating operation of one illustrativeembodiment of a variator that forms part of the toroidal traction driveautomatic transmission illustrated in FIG. 1.

FIG. 2B is a diagram further illustrating operation of the variator ofFIG. 2A.

FIG. 3 is a schematic diagram of one illustrative embodiment of theelectro-hydraulic control system that forms part of the toroidaltraction drive automatic transmission illustrated in FIG. 1.

FIG. 4 is a magnified view of the variator trim control sub-system ofthe electro-hydraulic control system illustrated in FIG. 3 showing theconfiguration of the variator trim control sub-system under oneoperating state of the variator multiplex valve.

FIG. 5 is a view similar to that of FIG. 4 showing the configuration ofthe variator trim control sub-system under another operating state ofthe variator multiplex valve.

DETAILED DESCRIPTION

For the purposes of promoting an understanding of the principles of theinvention, reference will now be made to a number of illustrativeembodiments shown in the attached drawings and specific language will beused to describe the same.

While the concepts of the present disclosure are susceptible to variousmodifications and alternative forms, specific exemplary embodimentsthereof have been shown by way of example in the drawings and willherein be described in detail. It should be understood, however, thatthere is no intent to limit the concepts of the present disclosure tothe particular forms disclosed, but on the contrary, the intention is tocover all modifications, equivalents, and alternatives falling withinthe spirit and scope of the invention as defined by the appended claims.

References in the specification to “one embodiment”, “an embodiment”,“an example embodiment”, etc., indicate that the embodiment describedmay include a particular feature, structure, or characteristic, butevery embodiment may not necessarily include the particular feature,structure, or characteristic. Moreover, such phrases are not necessarilyreferring to the same embodiment. Further, when a particular feature,structure, or characteristic is described in connection with anembodiment, it is submitted that it is within the knowledge of oneskilled in the art to effect such feature, structure, or characteristicin connection with other embodiments whether or not explicitlydescribed.

Referring now to FIG. 1, a block diagram is shown of one illustrativeembodiment of a system 10 for controlling operation of a toroidaltraction drive automatic transmission 14. In the illustrated embodiment,a power plant or energy center 12 is coupled to an automatictransmission 14 such that a rotatable output shaft 16 of the power plant12 is coupled to a rotatable input shaft 18 of the transmission 14 in aconventional manner. The input shaft 18 is coupled, in the illustratedembodiment, to a combination variator and gear set 20 that furtherincludes a plurality of selectively engageable friction devices, e.g.,one or more conventional, selectively engageable clutches or the like,and an output of the combination variator and gear set 20 is coupled toa rotatable output shaft 22. The combination variator and gear set 20 isillustratively controlled by an electro-hydraulic control system 24,some of the details of which will be described in greater detailhereinafter.

The power plant 12 is generally an apparatus that produces rotationaldrive power at the output shaft 16. Examples of the power plant 12include, but should not be limited to, one or any combination of a oneor more engines, such as an internal combustion engine of the sparkignited, compression ignition or other variety, a steam engine, or typeof engine that produces mechanical energy from one or more other fuelsources, one or more electrical generators, and the like.

The combination variator and gear set 20 illustratively includes aconventional full-toroidal, traction-drive variator that is coupled to aconventional gear set. Referring to FIGS. 2A and 2B, one illustrativeembodiment of some of the structural features of such a full-toroidal,traction-drive variator 40 is shown. In the illustrated embodiment, thevariator 40 includes a pair of opposing, toroidal-shaped disks 42 and 44that rotate independently of each other. For example, the disk 42 isillustratively directly connected to the input shaft 18 of thetransmission 14 such that the disk 42 is directly rotatably driven bythe power plant 12. Alternatively, the disk 42 may be connected to theinput shaft 18 of the transmission through one or more structures, e.g.,one or more gear sets or other structures. For purposes of thisdisclosure, the term “coupled” used to described the relationshipbetween the disk 42 and the input shaft 18 of the transmission isdefined as either a direct connection, i.e., engagement, between thedisk 42 and the input shaft 18 of the transmission 14 or an indirectconnection between the disk 42 and the input shaft 18 of thetransmission 14 through one or more structures interposed between thedisk 42 and the input shaft 18 of the transmission 14. Illustratively,the disk 44 is rigidly coupled to an output shaft 46 of the variator 40,and is rotatably coupled to the shaft 18 such that the disk 44 rotatesfreely about the shaft 18. The output shaft 46 of the variator 40 iscoupled directly, or indirectly through one or more transmission gears,to the output shaft 22 of the transmission 14 such that output shaft 46of the variator 40 drives one or more wheels of a vehicle (not shown)carrying the power plant 12 and transmission 14.

A number of rollers 48 are illustratively positioned between opposinginner, arcuate-shaped surfaces, e.g., concave surfaces, of the disks 42and 44, and a traction fluid (not shown) is disposed between the rollingsurface of each such roller 48 and the inner surfaces of the disks 42and 44. In the illustrated embodiment, the rolling surfaces of thevarious rollers 48 therefore do not contact, in a structural sense, theinner surface of either disk 42, 44; rather torque is transmitted by thevarious rollers 48 between the two disks 42, 44 via the traction fluid.It is because torque is transferred between the two disks 42, 44 via thetraction fluid and not via structural contact between the rollingsurfaces of the rollers 48 and the arcuate inner surfaces of the disks42, 44 that the variator is referred to as a traction-drive apparatus.

In the embodiment illustrated in FIGS. 2A and 2B, two such rollers 48 ₁and 48 ₂ are shown operatively positioned between the opposing innersurfaces of the two disks 42, 44. A roller actuator 50 ₁, e.g., in theform of a conventional hydraulically actuated piston, is coupled to theroller 48 ₁ via a bracket 52 ₁, and another roller actuator 50 ₂, e.g.,in the form of another conventional hydraulically actuated piston, iscoupled to the roller 48 ₂ via a bracket 52 ₂. It will be understoodthat the brackets 52 ₁ and 52 ₂ do not represent rotatable shafts aboutwhich the rollers 48 ₁ and 48 ₂ may be rotatably driven. Rather, thebrackets 52 ₁ and 52 ₂ represent structures about which the rollers 48 ₁and 48 ₂ rotate. In one actual implementation, for example, the brackets52 ₁ and 52 ₂ are configured to attach to the central hub of the rollers48 ₁ and 48 ₂ on either side thereof such that the brackets 52 ₁ and 52₂ and actuators 50 ₁ and 50 ₂ would extend generally perpendicular tothe page illustrating FIGS. 2A and 2B.

The hydraulically controlled actuators 50 ₁ and 50 ₂ are eachillustratively controllable by selectively controlling a high-sidehydraulic pressure applied to one side of the actuators 50 ₁ and 50 ₂and a low-side hydraulic pressure applied to the opposite side of theactuators 50 ₁ and 50 ₂. Traction force generated by the net hydraulicpressure, i.e., the difference between the applied high and low sidehydraulic pressures, is transmitted by the rollers 48 ₁ and 48 ₂ to thetwo disks 42, 44 via the traction fluid, and this applied traction forcedefines the torque transmitted between the two disks 42, 44. Thus, adirect relationship exists between the net hydraulic pressure applied tothe actuators 50 ₁ and 50 ₂ and the magnitude of the torque transmittedbetween the two disks 42, 44. Each roller 48 ₁ and 48 ₂ moves andprecesses to the location and tilt angle relative to the disks 42, 44required to transmit the torque to the disks 42, 44 defined by the nethydraulic pressure applied to the hydraulic actuators 50 ₁ and 50 ₂. Adifference in the magnitude of the net hydraulic pressure applied to theactuators 50 ₁ and 50 ₂ changes the torque transmitted to the outputshaft 46. The direction of the torque applied by the rollers 48 ₁ and 48₂ to the two disks 42, 44, is determined by the relative magnitudes ofthe high and low side pressures applied to the actuators 50 ₁ and 50 ₂.In one illustrative embodiment, for example, the rollers 48 ₁ and 48 ₂apply a positive torque to the two disks 42, 44 if the high sidehydraulic pressure is greater than the low side hydraulic pressure, andthe rollers 48 ₁ and 48 ₂ conversely apply a negative torque to the twodisks if the low side pressure is greater than the high side hydraulicpressure. In alternative embodiments, the rollers 48 ₁ and 48 ₂ mayapply a positive torque to the two disks 42, 44 if the low sidehydraulic pressure is greater than the high side hydraulic pressure, andthe rollers 48 ₁ and 48 ₂ may conversely apply a negative torque to thetwo disks if the high side pressure is greater than the low sidehydraulic pressure. In any case, the rollers 48 ₁ and 48 ₂ arefree-castoring, and are responsive to the actuators 50 ₁ and 50 ₂ toseek a position that provides the correct ratio match of engine anddrive train speeds based on input energy equaling output energy.

In one illustrative implementation, the variator 40 includes two sets orpairs of disks 42 and 44, with the pairs of the disks 42 rigidly coupledto each other and with the pairs of the disks 44 also rigidly coupled toeach other, such that the embodiment illustrated in FIGS. 2A and 2Brepresents one-half of such an implementation. In this illustrativeimplementation, three rollers are positioned between each opposing setof disks 42, 44 for a total of six rollers 48 ₁-48 ₆ and sixcorresponding hydraulically controlled actuators 50 ₁-50 ₆. It will beunderstood, however, that this particular implementation of the variator40 is shown and described only by way of example, and that otherembodiments of the variator 40 that include more or fewer pairs of disks42, 44, that include more or fewer rollers 48 and hydraulicallycontrolled actuators 50, and/or that are configured to be only partiallytoroidal in shape, may alternatively be used. It will further beunderstood that while the operation of the variator 40 is illustratedand described herein as being generally hydraulically controlled, thisdisclosure contemplates embodiments in which operation of the variator40 is controlled via purely electronic or electro-mechanical structures.

Referring again to FIG. 1, the gear set within the combination variatorand gear set 20 illustratively includes one or more conventionalplanetary gear set(s) and/or other gear set(s) that define(s) at leasttwo automatically selectable gear ratios and that is coupled to, orintegrated with, the variator, e.g., the variator 40 illustrated anddescribed with respect to FIG. 2. The combination variator and gear set20 further illustratively includes a number of conventional frictiondevices, e.g., clutches, which may be selectively controlled to therebycontrol shifting of the transmission 14 between the two or more gearratios. In alternate embodiments, the gear set may include more than oneplanetary gear set, one or more planetary gear sets in combination withone or more other conventional gear sets, or exclusively one or morenon-planetary gear sets.

In the example embodiment illustrated in FIG. 1, the transmission 14includes three friction devices, e.g., in the form of three conventionalclutches C1, C2 and C3. In this embodiment, each clutch C1, C2 and C3 isoperated in a conventional manner, e.g., via fluid pressure, under thecontrol of the electro-hydraulic control system 24. In this regard, afluid path 25 ₁ is fluidly coupled between the electro-hydraulic controlsystem 24 and the clutch C1, a fluid path 25 ₂ is fluidly coupledbetween the electro-hydraulic control system 24 and the clutch C2, and afluid path 25 ₃ is fluidly coupled between the electro-hydraulic controlsystem 24 and the clutch C3. The electro-hydraulic control system 24 isoperable to control operation of the clutches C1-C3 by controlling fluidpressure within the fluid paths 25 ₁-25 ₃ respectively.

The gear set and the clutches C1, C2 and C3 are illustratively arrangedto provide four separate modes of operation of the transmission 14, andthe various operating modes of the transmission 14 are selectivelycontrolled by the operation of the clutches C1, C2 and C3. In a firstoperating mode, M1, for example, the clutch C1 is applied, e.g.,engaged, while the clutches C2 and C3 are released, e.g., disengaged,and in this mode forward or reverse launch can be accomplished, and thevehicle carrying the transmission 14 can be operated at vehicle speedsup to about 10 miles per hour. In a second operating mode, M2, asanother example, the clutch C2 is engaged while the clutches C1 and C3are disengaged, and in this mode the vehicle can be operated at vehiclespeeds in the range of about 10-30 miles per hour. In a third operatingmode, M3, as yet another example, the clutch C3 is engaged while theclutches C1 and C2 are disengaged, and in this mode the vehicle can beoperated at vehicle speeds greater than about 30 miles per hour. In afourth mode, M0, as a final example, the clutches C1, C2 and C3 are alldisengaged, and in this mode the transmission 14 is in neutral. Withineach operating mode, torque applied to the output shaft 22 of thetransmission 14 is controlled by the variator, e.g., the variator 40. Inthe transitional states between the various operating modes M1, M2 andM3, the variator torque is illustratively reversed to assist transitionsfrom one operating mode to the next.

The system 10 further includes a transmission control circuit 30 thatcontrols and manages the overall operation of the transmission 14. Thetransmission control circuit 30 includes a number, M, of operatingparameter inputs, OP₁-OP_(M), that are electrically connected tocorresponding operating parameter sensors included within theelectro-hydraulic control system 24 via corresponding signal paths 26₁-26 _(M), wherein M may be any positive integer. The one or moreoperating parameter sensors included within the electro-hydrauliccontrol system 24, examples of which will be described hereinafter,produce corresponding operating parameter signals on the signal paths 26₁-26 _(M), which are received by the transmission control circuit 30.The transmission 14 further includes a number, N, of electricallycontrollable actuators included within the electro-hydraulic controlsystem 24 that are each electrically connected to different one of acorresponding number of actuator control outputs, AC₁-AC_(N) of thetransmission control circuit 30 via corresponding signal paths 28 ₁-28_(N), wherein N may be any positive integer. The one or moreelectrically controllable actuators included within theelectro-hydraulic control system 24, examples of which will be describedhereinafter, are responsive to actuator control signals produced by thetransmission control circuit 30 on the corresponding signal paths 28₁-28 _(N) to control various operational features of the transmission14.

Illustratively, the transmission control circuit 30 ismicroprocessor-based, and includes a memory unit 32 having instructionsstored therein that are executable by the control circuit 30 to controloperation of the transmission 14 generally, and more specifically tocontrol operation of the electro-hydraulic control system 24. It will beunderstood, however, that this disclosure contemplates other embodimentsin which the transmission control circuit 30 is notmicroprocessor-based, but is configured to control operation of thetransmission 14 generally and operation of the electro-hydraulic system24 more specifically, based on one or more sets of hardwiredinstructions and/or software instructions stored in the memory unit 32.

Referring now to FIG. 3, a schematic diagram is shown of oneillustrative embodiment of the electro-hydraulic control system 24 ofFIG. 1. In the illustrated embodiment, the electro-hydraulic controlsystem 24 is roughly divided into separate control sections; a variatorcontrol section 56 comprising a variator trim control sub-system 56A, avariator actuator sub-system 56B and a variator switching sub-system56C, a clutch control section 58, and a clutch and variator pressurecontrol section 98.

Referring specifically to the clutch and variator pressure controlsection 98, a conventional fluid pump 60 is configured to supplytransmission fluid, e.g., conventional transmission oil, to the variatortrim control section 56A, the variator switching and fault detectionsection 56C and to the clutch control section 58 from a source 64 oftransmission fluid, e.g., a conventional transmission sump 64. In oneillustrative embodiment, the fluid pump 60 is a conventionalpositive-displacement pump that is driven by the drive shaft 16 of theengine 12 via the input shaft 18 of the transmission 14, and is sizedand configured to supply pressurized fluid from the sump 64 to a numberof friction control devices, e.g., clutches, and to the variator. In theillustrated embodiment, a fluid inlet of the fluid pump 60 is fluidlycoupled to the sump 64 via a fluid passageway 62. A fluid outlet of thepump 60 is fluidly coupled via a clutch main fluid passageway 65 to afluid port and end of a dual pump pressure regulator valve 190, to afluid outlet of a check ball valve 101, to a fluid inlet of a variatortrim valve 70, to a fluid port of a variator pressure multiplex valve220, to a control main fluid passageway 104 via a conventional flowreducer, to a fluid port of a conventional main pressure regulator valve180 and a fluid inlet of a main clutch pressure relief valve 186, and tofluid ports of two trim valves 152 and 154 included in the clutchcontrol section 158. The clutch and variator pressure control section 98further includes another conventional fluid pump 100 configured tosupply transmission fluid, e.g., conventional transmission oil, to thedual pump pressure regulator valve 190 and, under some operatingconditions, to the fluid path 65 to thereby supplement the supply offluid by the fluid pump 60. In one illustrative embodiment, the fluidpump 100 is a conventional positive-displacement pump that is driven bythe drive shaft 16 of the engine 12 via the input shaft 18 of thetransmission 14, and is sized and configured to supply pressurized fluidto a conventional transmission lubrication system. In the illustratedembodiment, a fluid inlet of the fluid pump 100 is fluidly coupled tothe sump 64 via the fluid passageway 62. A fluid outlet of the pump 100is fluidly coupled via a fluid cooler/lube fluid passageway 102 to afluid port of the dual pump pressure regulator valve 190 and to a fluidinlet of the check ball valve 101. Under some operating conditions ofthe electro-hydraulic control system 24, the dual pump pressureregulator valve 190 directs fluid supplied by the fluid pump 100 to aconventional cooler and lubrication sub-system 160 of the transmission14 via a fluid path 162. In the illustrated embodiment, the fluid path162 is fluidly coupled to a fluid inlet of a cooler relief valve 164 andto a fluid inlet of a conventional cooler 166. A fluid outlet of thecooler 166 is fluidly coupled through a fluid filter 168 to a fluid portand end of a gear lubrication regulator valve 170 and to gearlubrication and variator lubrication passageways 172 and 174respectively. Further details relating to the structure and operation ofthe clutch and variator pressure control section 98 generally, and tothe structure and operation of the dual pump pressure regulator valve190 in particular, are described in co-pending U.S. patent applicationSer. No. ______, having attorney docket numberATP-0053-USP/46582-212953, the disclosure of which is incorporatedherein by reference in its entirety.

The control main fluid passageway 104 is fluidly coupled to fluid inletsand fluid ports of the control main pressure regulator valve 180 and aconventional control main pressure relief valve 182, to a fluid inlet ofa conventional control main pressure accumulator valve 184, to controlmain inputs of actuators 154, 158, 164, 168, 85 and 87 and to fluidports of valves 152, 154, 162, 96, 82, 88 and 76. The control mainpassageway 104 supplies control main fluid to the foregoing actuatorsand valves.

Referring now to the variator trim control sub-system 56A of thevariator control section 56, a variator main fluid passageway 68 is fed,under certain operating conditions as described in detail in co-pendingU.S. patent application Ser. No. ______, having attorney docket numberATP-0053-USP/46582-212953, by the clutch main fluid passageway 65 viathe dual pump pressure regulator valve 190. The variator main fluidpassageway 68 is fluidly coupled to a fluid inlet of a variator trimvalve 72 and to one end of a variator fault valve 76. The variator trimvalve 72 includes an actuator 84 that is electrically connected to thetransmission control circuit 30 via a signal path 28 ₂. Another fluidinlet of the variator trim valve 72 is fluidly coupled to exhaust, and afluid outlet of the variator trim valve 72 is fluidly coupled to an endof the variator fault valve 76 opposite the end to which the variatormain fluid passageway is coupled, and is also fluidly coupled through aconventional mode damper 118, to a fluid port of the variator pressuremultiplex valve 220. Another variator trim valve 70 includes an actuator74 that is electrically connected to the transmission control circuit 30via a signal path 28 _(k). One fluid inlet of the variator trim valve 70is fluidly coupled to the clutch main fluid passageway 65. Another fluidinlet of the variator trim valve 70 is fluidly coupled to exhaust, and afluid outlet of the variator trim valve 70 is fluidly coupled to anotherfluid port of the variator pressure multiplex valve 220. The actuators74 and 84 are illustratively conventional electronically actuatedsolenoids, and the trim valves 70 and 72 are illustrativelyvariable-bleed valves that supply variable-pressure transmission fluidbased on control signals produced by the transmission control circuit 30on the signal paths 28 ₁ and 28 ₂ respectively.

Under normal operating conditions, the variator pressure multiplex valve220 routes variator main fluid from the outlet of the mode damper 118 tothe variator switching sub-system 56C and routes the fluid outlet of thevariator trim valve 70 to an end chamber of the dual pump pressureregulator valve 190 such that under such normal operating conditions thevariator trim valve 72 controls the variator switching sub-system 56Cand the fluid pressures in the clutch main fluid passageway 65 and inthe endload passageway of the variator actuator control sub-system 56Bare modulated by the variator trim valve 70. Under other operatingconditions, e.g., during cold start and/or certain fault conditions, thevariator pressure multiplex valve 220 exhausts one end chamber of thedual pump pressure regulator valve 190 such that the dual pump regulatorvalve 190 regulates the fluid pressure in the clutch main fluidpassageway 65 (and thus the fluid pressures in the other main fluidpassageways) to a constant fluid pressure, and the variator pressuremultiplex valve 220 further routes fluid from the clutch main fluidpassageway 65 directly to the variator switching sub-system 56C suchthat under such other operating conditions the variator trim valve 70controls the variator switching sub-system 56C. Further details relatingto the structure and operation of the variator trim control sub-system56A are described hereinafter with respect to FIGS. 4-5.

Referring now to the variator actuator sub-system 56B of the variatorcontrol section 56, a fluid path 112 fluidly coupled to the variatorswitching sub-system 56C defines a variator high-side fluid passageway,51, and a fluid path 116 also fluidly coupled to the variator switchingsubsection 56C defines a variator low-side fluid passageway, S2. In theembodiment illustrated in FIG. 3, the variator includes six actuators,50 ₁-50 ₆, e.g., conventional pistons, and the variator high-side fluidpassageway 112 is fluidly coupled to the high side of each such actuator50 ₁-50 ₆ via a corresponding conventional damper 122 ₁-122 ₆. Aconventional check valve 126 is interposed between the variatorhigh-side fluid passageway 112 and a fluid passageway 128. The variatorlow-side fluid passageway 116 is fluidly coupled to the low side of eachactuator 50 ₁-50 ₆ via a corresponding conventional damper 136 ₁-136 ₆,and another conventional check valve 140 is interposed between thevariator low-side fluid passageway 116 and the fluid passageway 128. Thefluid passageway 128 is fluidly coupled to an endload relief valve 130,which is further fluidly coupled between the high side and the low sideof the actuator 50 ₆. Further details relating to one illustrativestructure and method of operating the endload relief valve 130 areprovided in co-pending U.S. Patent Application Ser. No. 61/287,020,having Attorney Docket No. 46582-209632 (ATP-0047-USP), the disclosureof which is incorporated herein by reference in its entirety.

The fluid passageway 128 is further fluidly coupled to another fluidpassageway 132, and an endload port or passageway 135 is fluidly coupledto another fluid passageway 134. In the state of the variator multiplexvalve 220 illustrated in FIG. 3, i.e., stroked, the fluid passageway 132is fluidly coupled via the variator pressure multiplex valve 220 to thefluid passageway 134 such that the fluid pressure within the endloadport or passageway 135 is supplied by the fluid passageway 128.Generally, the fluid pressure in the endload port or passageway 135 isthe pressure load on the variator disks required to keep the variatordisks from slipping. The pressure in the fluid passageway 128 under suchnormal operating conditions is variable, and is controlled by thevariator based on the fluid pressures 51 and S2. Under normal operatingconditions, such as illustrated in FIG. 3, the variator pressuremultiplex valve 220 fluidly couples the endload port or passageway 135directly to the fluid passageway 128 such that the fluid pressure in theendload fluid passageway 135 is modulated by the variable fluid pressurein the fluid passageway 128. Under other operating conditions, e.g.,cold start and certain fault conditions, the variator pressure multiplexvalve 220 routes a fluid at a fixed pressure, e.g., clutch main fluid inthe clutch main fluid passageway 65, to the endload fluid port orpassageway 135 via the fluid passageway 134, as is described in greaterdetail hereinafter.

A variator fault valve 76 is fluidly coupled between the variator mainfluid passageway 68 at one end and the fluid outlet of the variator trimvalve 72 at its opposite end. The variator fault valve 76 illustrativelyincludes a spool 142 which is responsive to a difference in pressurebetween the variator main fluid passageway 68 and the fluid outlet ofthe variator trim valve 72 to determine whether a variator fault exists.In the embodiment illustrated in FIG. 3, for example, if the fluidpressure in the variator main fluid passageway 68 is sufficientlygreater than that in the fluid outlet of the variator trim valve 72, thespool 142 is forced upwardly and thereby fluidly couples the exhaustbackfill fluid passageway (EB) 108 to the fluid passageway 144. This isthe position of the spool 142 illustrated in FIG. 3. If instead thefluid pressure in the fluid outlet of the variator trim valve 72 issufficiently greater than that in the variator main fluid passageway 68,the spool 142 is forced downwardly and thereby fluidly couples thecontrol main (COM) fluid passageway 104 to the fluid passageway 144.Illustratively, the variator fault valve 76 is designed to have aspecified amount of hysteresis between the two extreme positions of thespool 142, and in one embodiment the hysteresis is approximately 15-20%such that the differential pressure between variator main fluidpassageway 68 and the fluid outlet of the variator trim valve 72 must begreater than about 15-20% before the spool 142 changes position. Thoseskilled in the art will appreciate that this hysteresis value isprovided only by way of example and that other hysteresis values, or nohysteresis value, may alternatively be used.

Referring now to the variator switching sub-system 56C of the variatorcontrol section 56, a pair of variator control valves 82 and 88 eachinclude an actuator 85 and 95 respectively that is electricallyconnected to the transmission control circuit 30 via a signal path 28 ₃and 28 ₄ respectively. In the illustrated embodiment, the actuators 85and 95 are illustratively conventional electronically actuatedsolenoids. The actuators 85 and 95 are responsive to control signalsproduced by the transmission control circuit 30 on the signal paths 28 ₃and 28 ₄ respectively to selectively control the valves 82 and 88 tothereby selectively supply S1 and S2 fluid pressures provided by thevariator trim valve 72 under normal operating conditions, or provided bythe variator trim valve 70 under other operating conditions, e.g., coldstart and certain fault conditions, to the variator actuator sub-system56B of the variator control section 56. Further details relating to thestructure and operation of the variator control valves 82 and 88 aredescribed in co-pending U.S. patent application Ser. No. ______, havingattorney docket number ATP-0052-USP/46582-212952, the disclosure ofwhich is incorporated herein by reference in its entirety.

Referring now to the clutch control section 58, the clutch main fluidpassageway 65 is illustratively fluidly coupled to each of a pair ofclutch trim valves 150 and 152 which together define a trim system. Theclutch trim valves 150 and 152 each illustratively include an actuator154 and 158 respectively that is electrically connected to thetransmission control circuit 30 via a signal path 28 ₅ and 28 ₆respectively. One control fluid inlet of each of the clutch trim valves150 and 152 is fluidly coupled to the control main fluid passageway 104,and another control fluid inlet of each clutch trim valve 150 and 152 isfluidly coupled to exhaust. In the illustrated embodiment, the actuators154 and 158 are illustratively conventional electronically actuatedsolenoids. Fluid outlets of each of the clutch trim valves 150 and 152are fluidly coupled to fluid inlets of each of a pair of clutch controlvalves 162 and 96. The clutch trim valves 150 and 152 are eachconfigured to selectively, i.e., under the control of the transmissioncontrol circuit 30 via signals produced by the transmission controlcircuit 30 on the signal paths 28 ₅ and 28 ₆ respectively, fluidlycouple the clutch main fluid passageway 65 to the clutch control valves162 and 96.

The clutch control valves 162 and 96 each illustratively include anelectronic actuator, e.g., an electrically controlled solenoid, 164 and168 respectively that is electrically connected to the transmissioncontrol circuit 30 via a signal path 28 ₇ and 28 ₈ respectively. Onecontrol fluid inlet of each clutch control valve 162 and 96 is fluidlycoupled to the control main, COM, fluid passageway 104, and anothercontrol fluid inlet is fluidly coupled to exhaust. The clutch controlvalve 96 is further fluidly coupled directly to the C2 clutch fluid path25 ₂, and clutch main fluid or exhaust backfill is selectively appliedto the C2 clutch via the fluid path 25 ₂ via various combinations ofstates of the actuators 154, 158, 164 and 168. The clutch control valve162 is further fluidly coupled directly to each of the C1 and C3 clutchfluid paths 25 ₁ and 25 ₃, and clutch main fluid or exhaust backfill isselectively routed through the clutch control valve 162 to the C1 clutchvia the fluid passageway 25 ₁ or to the C3 clutch via the fluidpassageway 25 ₃ via various combinations of states of the actuators 154,158, 164 and 168. The clutches C1-C3 are thus selectively activated,i.e., engaged, and deactivated, i.e., disengaged, based on the operatingstates of the actuators 154, 158, 164 and 168 of the clutch trim valves150 and 152 and the clutch control valves 162 and 96 respectively, byselectively routing clutch main fluid and exhaust backpressure throughthe control valves 162 and 96 to the various clutches C1-C3.

Further details relating to the structure and operation of the clutchcontrol subsection 58 are provided in co-pending U.S. Patent ApplicationSer. No. 61/287,031, having Attorney Docket No. 46582-209546(ATP-0043-USP), and in co-pending U.S. Patent Application Ser. No.61/287,038, having Attorney Docket No. 46582-209547 (ATP-0044-USP), thedisclosures of which are both incorporated herein by reference in theirentireties.

In the illustrated embodiment, sensors are operatively positionedrelative to the variator fault valve 76, the variator control valve 88,the clutch trim valve 154 and each of the clutch control valves 162 and96 to enable monitoring of the operating states of each of the valves76, 88, 154, 162 and 96 and to further monitor certain transmissionoperating state faults. In one illustrative embodiment, such sensors areprovided in the form of conventional pressure switches, although it willbe understood that a conventional pressure sensor may be substituted forany one or more of the pressure switches. In the illustrated embodiment,for example, a pressure switch 146 is fluidly coupled to a fluid port ofthe variator control valve 88, and is electrically connected to thetransmission control circuit 30 via a signal path 26 ₁. Another pressureswitch 148 is fluidly coupled to the fluid port 144 of the variatorfault valve 76, and is electrically connected to the transmissioncontrol circuit 30 via a signal path 26 ₂. Still another pressure switch184 is fluidly coupled to a fluid port of the clutch control valve 162,and is electrically connected to the transmission control circuit 30 viaa signal path 26 ₃. Yet another pressure switch 188 is fluidly coupledto a fluid port of the clutch control valve 96, and is electricallyconnected to the transmission control circuit 30 via a signal path 26 ₄.A further pressure switch 186 is fluidly coupled to a fluid port of theclutch trim valve 154, and is electrically connected to the transmissioncontrol circuit 30 via a signal path 26 ₅.

Signals produced by the pressure switches 146, 148, 184, 188 and 186 areprocessed by the transmission control circuit 30 to allow monitoring anddiagnosis by the transmission control circuit 30 of the states of thesepressure switches and thus the operating states of the each of thevalves 76, 88, 154, 162 and 96. For example, in the embodimentillustrated in FIG. 3, the pressure switch 148 is configured to producea signal corresponding to the state, e.g., normal or variator fault, ofthe variator fault valve 76. If the fluid pressure in the variator mainfluid passageway 68 is sufficiently greater than that in the fluidoutlet of the variator trim valve 72 such that the spool 142 is forcedupwardly and thereby fluidly couples the exhaust backfill fluidpassageway (EB) 108 to the fluid passageway 144, as illustrated in FIG.3, this corresponds to normal operation of the variator in which thepressure switch 148 produces a low or logical “0” signal. If instead thefluid pressure in the fluid outlet of the variator trim valve 72 issufficiently greater than that in the variator main fluid passageway 68,the spool 142 is forced downwardly (not shown in the FIGS) which causesthe spool 142 to fluidly couple the control main (COM) fluid passageway104 to the fluid passageway 144. This corresponds to a variator faultconditions and the pressure switch 148 under such a variator faultcondition switches to a high or logical “1” state. Thus, under normaloperating conditions the pressure switch 148 produces a low or “0”signal, and under variator fault conditions the pressure switch 148produces a high or “1” signal. The memory 32 of the transmission controlcircuit 30 Illustratively includes instructions stored therein that areexecutable by the control circuit 30 to process the signal produced bythe pressure switch 148 to determine whether the variator is operatingnormally or whether a variator fault exists.

Further details relating to diagnosis of the signals produced by thepressure switch 146 will be described hereinafter. Further detailsrelating to diagnosis of the signals produced by the pressure switches184, 186 and 188 are described in co-pending U.S. Patent ApplicationSer. No. 61/287,031, having Attorney Docket No. 46582-209546(ATP-0043-USP).

Referring now to FIGS. 4-5, further details relating to the structureand operation of the variator trim control sub-system 56A of thevariator control section 56 are illustrated. In the embodimentillustrated in FIGS. 4-5, like reference numbers are used to identifylike components illustrated in FIG. 3. Referring specifically to theclutch and variator pressure control section 98, the fluid pump 60 isfluidly coupled to one end of the dual pump pressure regulator valve 190via the clutch main fluid passageway 65, and the fluid pump 100 isfluidly coupled to the dual pump pressure regulator valve 190 via afluid passageway 102. A check ball valve 101 is positioned between thefluid passageways 65 and 102, and a ball 103 is positioned within thevalve 101 which opens when the fluid pressure in the fluid passageway102 exceeds that in the fluid passageway 65 by at least a predefinedpressure value such that fluid in the fluid passageway 102 can then flowfrom the fluid passageway 102 into the fluid passageway 65 under certainoperating conditions. The dual pump pressure regulator valve 190includes a spool 200 that axially translates under pressure within thevalve 190, e.g., within a conventional valve housing (not shown). Thespool 200 defines a number of lands consecutively and sequentiallypositioned along the spool 200 from one end 202 to an opposite end 204.The end of the valve 190 in which the end 202 of the spool 200translates is fluidly coupled via a conventional flow reducer to theclutch main fluid passageway 65. A spool base 208 is positioned withinand at a terminal end of a spring pocket 210, and a conventional valvespring 206 engages and extends between the end 204 of the spool 200 andthe spool base 208. The valve spring 206 is compressed and thereforeexerts a spring bias or spring force between and against the spool base208 and the end 204 of the spool 200. Because the position of the spoolbase 208 is fixed at one end of the spring pocket 210, the spool 200 isunder bias of the valve spring 206 in the direction of the spool end202. The spring pocket 210 of the dual pump pressure regulator valve 190is further fluidly coupled to a fluid outlet of the variator pressuremultiplex valve 220 via a fluid passageway 254. The fluid passageway 162fluidly connected to the lubrication and cooling sub-system 160 isfluidly coupled to the dual pump pressure regulator valve 190 via twoseparate fluid passageways.

As described hereinabove, the clutch main fluid passageway 65 is fluidlycoupled to a fluid inlet of the variator trim valve 70 via a fluidpassageway 250. The variator trim valve 70 is illustratively aconventional variable-bleed valve that receives fluid at one fluid inletfrom the clutch main fluid passageway 65, receives exhaust at anotherfluid inlet, and operates in a conventional manner to supplyvariable-pressure transmission fluid at its outlet based on a controlsignal produced by the transmission control circuit 30 on the signalpath 28 ₁. The control signal on the signal path 28 ₁ is received by aconventional solenoid 74 which serves as an actuator of the variatortrim valve 70. The fluid outlet of the variator trim valve 70 is fluidlycoupled to the variator pressure multiplex valve 220 via the fluidpassageway 252. Under normal operating conditions of the transmission14, such as illustrated and will be described with respect to FIG. 4,the variator pressure multiplex valve 220 fluidly couples the fluidpassageway 252 to the fluid passageway 254 such that thevariable-pressure transmission fluid produced by the variator trim valve70 at its fluid outlet is supplied to the spring pocket 210 of the dualpump pressure regulator valve 190. Under such normal operatingconditions, the position of the spool 200 within the dual pump pressureregulator valve 190 is defined by the fluid pressure at the end 202 ofthe spool 200, the fluid pressure at the opposite end 204 of the spool200, i.e., the fluid pressure within the spring pocket 210, and thebiasing force of the valve spring 206. Under certain other predefinedoperating conditions of the transmission 14, such as illustrated andwill be described with respect to FIG. 5, the variator pressuremultiplex valve 220 fluidly couples a fixed reference pressure to thefluid passageway 254 such that the fixed reference pressure is suppliedto the spring pocket 210 of the dual pump pressure regulator valve 190.In one illustrative embodiment, the fixed reference pressure is exhaust,and the variator pressure multiplex valve 220 therefore fluidly couplesthe fluid passageway 254 to an exhaust passageway 272, as illustrated inFIG. 5, to exhaust the spring pocket 210 of the dual pump regulatorvalve 190 under the certain other predefined operating conditions of thetransmission 14. In this embodiment, the position of the spool 200within the dual pump pressure regulator valve 190 under such otherpredefined operating conditions is defined by the fluid pressure at theend 202 of the spool 200, the area of the face of the end 202 of thespool 200 and the biasing force of the valve spring 206. In alternativeembodiments, the fixed reference pressure may be a fixed pressuregreater than exhaust, and in such embodiments the position of the spool200 within the dual pump pressure regulator valve 190 under the otherpredefined operating conditions is defined by the pressure at the end202 of the spool 200, the biasing force of the valve spring 206 and thefixed reference pressure within the spring pocket 210. The otherpredefined operating conditions may include a fault condition associatedwith the operation of the transmission 14 or sub-system, component orsection thereof. Alternatively or additionally, the predefined operatingconditions may include a cold start operating condition corresponding tolow temperature operation of the transmission 14 such as when startingthe power plant 12 and beginning operation in cold weather, e.g.,outside ambient temperature below a threshold temperature. Those skilledin the art will recognize one or more additional operating conditionsthat may define or be included with the other predefined operatingconditions, and such one or more additional operating conditions arecontemplated by this disclosure. In any case, further details relatingto the operation of the variator pressure control section 98 generallyand of the dual pump regulator valve 190 specifically during normal andthe one or more other predefined operating conditions are described inco-pending U.S. patent application Ser. No. ______, having AttorneyDocket No. 46582-212953 (ATP-0053-USP).

The variator main fluid passageway 68 is fluidly coupled between thedual pump pressure regulator valve 190 and the variator trim valve 72.The variator trim valve 72 is illustratively a conventionalvariable-bleed valve that receives fluid at one fluid inlet from thevariator main fluid passageway 68, receives exhaust at another fluidinlet, and operates in a conventional manner to supply variable-pressuretransmission fluid at its outlet based on a control signal produced bythe transmission control circuit 30 on the signal path 28 ₂. The controlsignal on the signal path 28 ₂ is received by a conventional solenoid 84which serves as an actuator of the variator trim valve 72. The fluidoutlet of the variator trim valve 72 is fluidly coupled to a fluid inletof the mode damper 118 via a fluid passageway 260, and the fluid outletof the mode damper 118 is fluidly coupled to the variator pressuremultiplex valve 220 via the fluid passageway 262. Under normal operatingconditions of the transmission 14, such as illustrated and will bedescribed with respect to FIG. 4, the variator pressure multiplex valve220 fluidly couples the fluid passageway 262 to a fluid passageway 264that is fluidly coupled to the variator switching sub-system 56C suchthat the variable-pressure transmission fluid produced by the variatortrim valve 72 at its fluid outlet is supplied to the variator switchingsub-system 56C. Under the other predefined operating conditions, such asillustrated and will be described with respect to FIG. 5, the variatorpressure multiplex valve 220 fluidly couples the fluid passageway 252 tothe fluid passageway 264 such that the variable-pressure transmissionfluid produced by the variator trim valve 70 at its fluid outlet issupplied to the variator switching sub-system 56C.

The variator switching sub-system 56C, illustrated in block diagram formin FIGS. 4 and 5, receives pressurized fluid from the variator trimvalve 70 or the variator trim valve 72 via the fluid passageway 264. Thevariator switching sub-system 56C also receives a lower pressure fluid,and in the illustrated embodiment the variator switching sub-system 56Cis fluidly coupled to the exhaust backfill (EB) fluid path 108, suchthat the lower pressure fluid is illustratively exhaust or ambientpressure. The variator switching sub-system 56C is fluidly coupled tothe variator actuator sub-system 56B, which is also illustrated in blockdiagram form in FIGS. 4 and 5, via fluid passageways 112 and 116. Asdescribed hereinabove, the fluid passageway 112 carries the “high side”fluid, 51, supplied to one side, i.e., the high side, of the pistonactuators 50 ₁-50 ₆, and the fluid passageway 116 carries the “low side”fluid, S2, supplied to the opposite side, i.e., the low side, of thepiston actuators 50 ₁-50 ₆. As described in detail in co-pending U.S.patent application Ser. No. ______, having Attorney Docket No.46582-212952 (ATP-0052-USP), the variator switching sub-system 56Cselectively supplies the higher pressure fluid in the fluid passageway264 and the lower pressure fluid, e.g., exhaust backfill, to one or theother of the S1 and S2 fluid passageways 112 and 116 to thereby controloperation of the variator actuator sub-system 56B. Those skilled in theart will recognize that other low pressure fluids may be supplied to thevariator switching sub-system 56C in place of exhaust backfill 108, andany such other low pressure fluids are contemplated by this disclosure.In any case, during normal operating conditions, as illustrated in FIG.4, the variator multiplex valve 220 thus directs the high or higherpressure fluid supplied by the variator trim valve 72 to the variatorswitching sub-system 56 via the fluid passageway 264, and during theother predefined operating conditions, as illustrated in FIG. 5, thevariator multiplex valve 220 directs the high or higher pressure fluidsupplied by the variator trim valve 70 to the variator switchingsub-system 56C. The low or lower pressure fluid supplied to the variatorswitching sub-system 56C is illustratively exhaust backfill 108 underboth normal operating conditions and the other one or more predefinedoperating conditions. The variator actuator sub-system 56B is responsiveto the high and low side fluids S1 and S2 to control torque produced bythe variator as described hereinabove.

The variator multiplex valve 220 illustratively includes a spool 222which sequentially defines a number of lands 224, 226, 228, 230 and 232thereon between one end 236 and an opposite end 240 thereof. The end 236resides in a spring pocket 234 of the valve 220 in which a valve spring238 resides and exerts a biasing force on the end 236 of the spool 222to thereby bias the spool 222 in the direction of the end 240 of thespool 222. The spring pocket 234 is exhausted at all times. The end 240of the spool 222 is fluidly coupled to the outlet of a solenoid actuator168 of the clutch control valve 96 via a fluid passageway 242, and thespring pocket 234 of the valve 220 is fluidly coupled to a spring pocket218 of the clutch control valve 96 via a fluid passageway 244. Theclutch control valve 96 likewise includes a spool 211 sequentiallydefining a number of lands thereon between one end 212 fluidly coupledto the fluid outlet of the actuator 168 and an opposite end 214extending into the spring pocket 218. A valve spring 216 is positionedin the spring pocket 218 of the clutch control valve 96, and the valvespring 216 exerts a biasing force against the end 214 of the spool 211in the direction of the end 212 of the spool 211. One fluid inlet of theactuator 168 receives control main fluid from the control main fluidpassageway 104 and another fluid inlet of the actuator 168 is fluidlycoupled to exhaust, and the fluid outlet is fluidly coupled to the end212 of the spool 211. The clutch control valve 96 is illustratively aconventional on-off valve that operates in a conventional manner basedon control signals produced by the transmission control circuit 30 onthe signal path 28 ₈ and received by the solenoid actuator 168 to strokeand destroke the valve 96.

The memory 32 of the control circuit 30 has instructions stored thereinthat are executable by the control circuit 30 to control operation ofthe variator trim valves 70 and 72 and operation of the clutch controlvalve 96. During normal operation, as illustrated in FIG. 4, the controlcircuit 30 illustratively controls the actuator 168 to stroke the clutchcontrol valve 96 by supplying the control main fluid in the fluidpassageway 104 to the end 212 of the spool 211. The spring pocket 218 isexhausted at all times, and the pressure of the control main fluid inthe fluid passageway 104 is controlled to be sufficient to overcome thebiasing force of the valve spring 216 when the clutch control valve 96is stroked such that, when stroked, the spool 211 is positioned awayfrom the fluid outlet of the actuator 168 as illustrated in FIG. 4. Inthis position, the fluid passageway 242 receives the control main fluidin the fluid passageway 104, which is applied to the end 240 of thespool 222 of the variator multiplex valve 220. The spring pocket 234 ofthe variator multiplex valve 220 is exhausted, and the spool 222 isforced under pressure of the control main fluid against the valve spring238 such that the valve spring 238 compresses and the end 240 of thespool 222 moves away from the fluid passageway 242 as illustrated inFIG. 4. The position of the spool 222 illustrated in FIG. 4 representsthe stroked state of the variator multiplex valve 220, which occurs whenthe clutch control valve 96 is also stroked. As described hereinabove,the valves 96 and 220 are stroked as illustrated in FIG. 4 under normaloperating conditions of the transmission 14.

During the one or more other predefined operating conditions of thetransmission 14, as illustrated in FIG. 5, the control circuit 30illustratively controls the actuator 168 to destroke the clutch controlvalve 96 by supplying exhaust to the end 212 of the spool 211. Becausethe spring pocket 218 is also exhausted the biasing force of the valvespring 216 forces the spool 211 upwardly such that, when destroked, theend 212 of the spool 211 is positioned adjacent to the fluid outlet ofthe actuator 168 as illustrated in FIG. 5. In this position, the fluidpassageway 242 is exhausted, which exhausts the end 240 of the spool 222of the variator multiplex valve 220. The spring pocket 234 of thevariator multiplex valve 220 is also exhausted, and the spool 222 isthus forced downwardly under the biasing force of the valve spring 238such that the end 240 of the spool 222 is positioned adjacent to thefluid passageway 242 as illustrated in FIG. 5. The position of the spool222 illustrated in FIG. 5 represents the destroked state of the variatormultiplex valve 220, which occurs when the clutch control valve 96 isalso destroked. As described hereinabove, the valves 96 and 220 aredestroked as illustrated in FIG. 5 under the one or more otherpredefined operating conditions of the transmission 14, e.g., faultconditions and/or cold start conditions.

It will be understood that while the variator multiplex valve 220 isillustrated in FIGS. 3-5 as being plumbed to mimic the operating state,i.e., stroked or destroked, of the clutch control valve 96, the variatormultiplex valve 220 may alternatively be plumbed to assume the oppositeof the operating state of the clutch control valve 96.

The clutch main fluid passageway 65 is further fluidly coupled to thevariator multiplex valve 220 directly and via a fluid passageway 270.The fluid passageway 132 that is fluidly coupled to the fluid passageway128 of the variator actuator sub-system 56B (see FIG. 3), and the fluidpassageway 134 that is fluidly coupled to the endload port or passageway135 of the variator actuator sub-system 56B (FIG. 3) are both fluidlycoupled to the variator multiplex valve 220.

Under normal operating conditions, as illustrated in FIG. 4, thevariator pressure multiplex valve 220 is stroked because the clutchcontrol valve 96 is stroked, and the variator main fluid supplied at theoutlet of the mode damper 118 is routed by the variator pressuremultiplex valve 220 between the two lands 228 and 230 to the variatorswitching sub-system 56C, and the fluid passageway 252 fluidly coupledto the fluid outlet of the variator trim valve 70 is routed by thevariator pressure multiplex valve 220 between the two lands 230 and 232to the spring pocket 210 of the dual pump pressure regulator valve 190.Under such normal operating conditions the variator trim valve 72 thussupplies the high pressure fluid to the variator switching sub-system56C, and the variator trim valve 70 supplies modulated, i.e., variable,fluid pressure to the spring pocket 210 of the dual pressure regulatorvalve 190. The variator switching sub-system 56C selectively applies thehigh pressure fluid supplied by the variator trim valve 72 to one of theS1 and S2 fluid passageways 112 and 116, and applies the low pressurefluid supplied by the fluid passageway 108 to the other of the S1 and S2fluid passageways 112 and 116 under such normal operating conditions asdescribed in greater detail in co-pending U.S. patent application Ser.No. ______, having Attorney Docket No. 46582-212952 (ATP-0052-USP). Thedual pressure regulator valve 190 is responsive to the modulated fluidpressure supplied by the fluid outlet of the variator trim valve 70 tothe spring pocket 210 of the valve 190 to regulate the pressure of fluidin the clutch main fluid passageway 65 as described in greater detailhereinabove and in co-pending U.S. patent application Ser. No. ______,having Attorney Docket No. 46582-212953(ATP-0053USP). Further under thenormal operating conditions, the variator trim valve 220 fluidly couplesthe clutch main fluid passageways 65 and 270 between the lands 226 and228 of the spool 222, and further couples the fluid passageways 132 and134 between the lands 224 and 226 of the spool 222. Under the normaloperating conditions, the variator multiplex valve 220 thus fluidlycouples the endload fluid passageway 135 to the variable pressure fluidpassageway 128 of the variator such that fluid pressure in the endloadfluid passageway 135 is variably controlled by the variator.

Under other one or more other predefined operating conditions, asillustrated in FIG. 5, the variator pressure multiplex valve 220 isdestroked because the clutch control valve 96 is destroked, and thevariator main fluid supplied at the outlet of the mode damper 118 isblocked by the land 228 of the spool 222 of the variator pressuremultiplex valve 220, and the fluid passageway 252 fluidly coupled to theoutlet of the variator trim valve 70 is routed by the variator pressuremultiplex valve 220 between the two lands 228 and 230 to the variatorswitching sub-system 56C. Under such one or more other predefinedoperating conditions, the variator trim valve 70 thus supplies the highpressure fluid to the variator switching sub-system 56C, and the fluidoutlet of the variator trim valve 72 is blocked by the variatormultiplex valve 220. The variator switching sub-system 56C selectivelyapplies the high pressure fluid supplied by the variator trim valve 70to one of the S1 and S2 fluid passageways 112 and 116, and applies thelow pressure fluid supplied by the fluid passageway 108 to the other ofthe S1 and S2 fluid passageways 112 and 116 under such one or morepredefined operating conditions as described in greater detail inco-pending U.S. patent application Ser. No. ______, having AttorneyDocket No. 46582-212952 (ATP-0052-USP). The variator multiplex valve 220further routes the exhaust fluid passageway 272 to the spring pocket 210of the dual pump pressure regulator valve 190 under the one or morepredefined operating conditions such that the spring pocket 210 of thevalve 190 received exhaust, i.e., ambient pressure. The dual pressureregulator valve 190 is responsive to the fixed reference fluid pressure(e.g., exhaust) supplied by the variator multiplex valve 220 to thespring pocket 210 of the valve 190 to regulate the pressure of fluid inthe clutch main fluid passageway 65 to a fixed fluid pressure asdescribed in greater detail hereinabove and in co-pending U.S. patentapplication Ser. No. ______, having Attorney Docket No.46582-212953(ATP-0053USP).

Further under the one or more predefined operating conditions, thevariator multiplex valve 220 fluidly couples the fluid passageway 270 tothe exhaust passageway 272 between the lands 226 and 228 of the spool222, and fluidly couples the clutch main fluid passageway 65 to thefluid passageway 134 between the lands 224 and 226 of the spool 222while blocking the fluid passageway 132 with the land 224. Under the oneor more predefined operating conditions of the transmission 14, thevariator multiplex valve 220 thus fluidly couples the endload fluidpassageway 135 to the clutch main fluid passageway 65 such that fluidpressure in the endload fluid passageway 135 is controlled to the fixedpressure in the clutch main fluid passageway 65. As describedhereinabove, the one or more predefined operating conditions may be orinclude at least one of a certain one or more fault conditions and acold start condition.

It will be understood that while the variator multiplex valve 220 isillustrated in FIGS. 3-5 as being plumbed such that higher pressurefluid is supplied by the variator trim valve 72 to the variatorswitching sub-system 56C when the variator multiplex valve 220 isstroked and the higher pressure fluid is supplied by the variator trimvalve 70 to the variator switching sub-system 56C when the variatormultiplex valve 220 is destroked, the variator multiplex valve 220 mayalternatively be plumbed such that higher pressure fluid is supplied bythe variator trim valve 72 to the variator switching sub-system 56C whenthe variator multiplex valve 220 is destroked and the higher pressurefluid is supplied by the variator trim valve 70 to the variatorswitching sub-system 56C when the variator multiplex valve 220 isstroked.

While the invention has been illustrated and described in detail in theforegoing drawings and description, the same is to be considered asillustrative and not restrictive in character, it being understood thatonly illustrative embodiments thereof have been shown and described andthat all changes and modifications that come within the spirit of theinvention are desired to be protected.

1. An apparatus for controlling fluid flow to a variator in an automatictransmission, the variator responsive to separate high and low pressurefluids to control an output torque of the variator, the apparatuscomprising: a first trim valve responsive to a first control signal tosupply a first fluid at a fluid outlet thereof, a second trim valveresponsive to a second control signal to supply a second fluid at afluid outlet thereof, a variator switching sub-system controllablysupplying the high pressure fluid and the low pressure fluid to thevariator, and a multiplex valve fluidly coupled to the outlets of thefirst and second trim valves, the multiplex valve supplying the firstfluid supplied by the first trim valve as the high pressure fluid to thevariator switching sub-system during at least one predefined operatingcondition of the automatic transmission and otherwise supplying thesecond fluid supplied by the second trim valve as the high pressurefluid to the variator switching sub-system.
 2. The apparatus of claim 1further comprising a control circuit including a memory havinginstructions stored therein executable by the control circuit to producethe first and second control signals, wherein the at least onepredefined operating condition comprises at least one of a faultcondition associated with the automatic transmission and a cold startcondition.
 3. The apparatus of claim 1 wherein the multiplex valvecomprises a spool having a stroked operating state and a destrokedoperating state, the multiplex valve supplying the first fluid as thehigh pressure fluid to the variator switching sub-system in one of thestroked operating state and the destroked operating state, and themultiplex valve supplying the second fluid as the high pressure fluid tothe variator switching sub-system in the other one of the strokedoperating state and the destroked operating state.
 4. The apparatus ofclaim 3 further comprising a control valve responsive to a third controlsignal to control the multiplex valve to the stroked operating state andto a fourth control signal to control the multiplex valve to thedestroked operating state.
 5. The apparatus of claim 4 furthercomprising a control circuit including a memory having instructionsstored therein executable by the control circuit to produce one of thethird and fourth control signals to control the control valve to theother one of the stroked operating state and the destroked operatingstate during the at least one predefined operating condition, andwherein the at least one predefined operating condition comprises atleast one of a fault condition associated with the automatictransmission and a cold start condition.
 6. The apparatus of claim 1further comprising a regulator valve fluidly coupled by the multiplexvalve to a reference pressure during the at least one predefinedoperating condition, the regulator valve also fluidly coupled to a mainfluid passageway that is further fluidly connected to a fluid inlet ofthe first trim valve, the regulator valve responsive to the referencepressure to regulate fluid pressure in the main fluid passageway to afixed pressure main fluid during the at least one predefined operatingcondition, the fluid outlet of the first trim valve fluidly coupled bythe multiplex valve to the variator switching sub-system during the atleast one predefined operating condition, the first trim valveresponsive to the first control signal to supply the first fluid to thevariator switching sub-system as the high pressure fluid based on thefixed pressure main fluid during the at least one predefined operatingcondition.
 7. The apparatus of claim 6 wherein the main fluid passagewayis further fluidly coupled by the regulator valve to a fluid inlet ofthe second trim valve, the second trim valve responsive to the secondcontrol signal to supply the second fluid to the multiplex valve basedon the fixed pressure main fluid during the at least one predefinedoperating condition, the multiplex valve blocking the second fluid fromthe variator switching sub-system during the at least one predefinedoperating condition.
 8. The apparatus of claim 6 wherein the variatorhas at least one roller between a first torroidal disk coupled to aninput of the automatic transmission and a second torroidal disk coupledto an output of the automatic transmission, and wherein the variator isfluidly coupled to an endload fluid passageway, the endload fluidpassageway defining therein an endload pressure corresponding to apressure load on the first and second torroidal disks required to keepthe first and second torroidal disks from slipping, and wherein theendload fluid passageway is fluidly coupled to the multiplex valve, themultiplex valve fluidly coupling the endload fluid passageway to themain fluid passageway to thereby supply the fixed pressure main fluid tothe endload fluid passageway during the at least one predefinedoperating condition.
 9. The apparatus of claim 4 further comprising acontrol circuit including a memory having instructions stored thereinexecutable by the control circuit to produce the other one of the thirdand fourth control signals to control the control valve to the one ofthe stroked operating state and the destroked operating state duringoperating conditions other than the at least one predefined operatingcondition.
 10. The apparatus of claim 1 further comprising a regulatorvalve fluidly coupled by the multiplex valve to the fluid outlet of thefirst trim valve during operating conditions other than the at least onepredefined operating condition, the regulator valve also fluidly coupledto a main fluid passageway that is further fluidly connected to a fluidinlet of the first trim valve, the first trim valve responsive to thefirst control signal to supply the first fluid to the fluid outlet ofthe first trim valve based on pressure of fluid in the main fluidpassageway during the operating conditions other than the at least onepredefined operating condition, the regulator valve responsive to thefirst fluid to regulate fluid pressure in the main fluid passagewayduring the operating conditions other than the at least one predefinedoperating condition.
 11. The apparatus of claim 10 wherein the mainfluid passageway is further fluidly coupled by the regulator valve to afluid inlet of the second trim valve, the fluid outlet of the secondtrim valve fluidly coupled by the multiplex valve to the variatorswitching sub-system during the operating conditions other than the atleast one predefined operating condition, the second trim valveresponsive to the second control signal to supply the second fluid tothe fluid outlet of the second trim valve as the high pressure fluidbased on fluid pressure in the main fluid passageway during theconditions other than the at least one predefined operating condition.12. The apparatus of claim 10 wherein the variator has at least oneroller between a first torroidal disk coupled to an input of theautomatic transmission and a second torroidal disk coupled to an outputof the automatic transmission, and wherein the variator is fluidlycoupled to an endload fluid passageway, the endload fluid passagewaydefining therein an endload pressure corresponding to a pressure load onthe first and second torroidal disks required to keep the first andsecond torroidal disks from slipping, and wherein the endload fluidpassageway is fluidly coupled to the multiplex valve, the multiplexvalve fluidly coupling the endload fluid passageway to a variablepressure fluid passageway of the variator such that fluid pressure inthe endload fluid passageway is variably controlled by the variatorduring the operating conditions other than the at least one predefinedoperating condition.
 13. A method for controlling fluid flow to avariator in an automatic transmission, the variator responsive toseparate high and low pressure fluids supplied by a variator switchingsub-system to control an output torque of the variator, the methodcomprising: supplying a first fluid supplied by a first trim valve asthe high pressure fluid to the variator switching sub-system during atleast one predefined operating condition of the automatic transmission,and supplying a second fluid supplied by a second trim valve separatefrom the first trim valve as the high pressure fluid to the variatorswitching sub-system during operating conditions other than the at leastone predefined operating condition.
 14. The method of claim 13 whereinthe first fluid supplied by the first trim valve to the variatorswitching sub-system as the high pressure fluid during the at least onepredefined operating condition of the automatic transmission is avariable pressure fluid.
 15. The method of claim 14 wherein the firstfluid supplied by the first trim valve to the variator switchingsub-system as the high pressure fluid during the at least one predefinedoperating condition is derived from a main fluid, and wherein the methodfurther comprises regulating pressure of the main fluid to a fixedpressure based on a fixed reference pressure during the at least onepredefined operating condition.
 16. The method of claim 15 wherein thefixed reference pressure is ambient pressure.
 17. The method of claim 13wherein the second fluid supplied by the second trim valve to thevariator switching sub-system as the high pressure fluid during theoperating conditions other than the at least one predefined operatingcondition of the automatic transmission is a variable pressure fluid.18. The method of claim 17 wherein the variable pressure second fluidsupplied by the second trim valve to the variator switching sub-systemas the high pressure fluid during the operating conditions other thanthe at least one predefined operating condition is derived from a mainfluid, and wherein the method further comprises modulating fluidpressure of the main fluid based on the first fluid supplied by thefirst trim valve during the operating condition other than the at leastone predefined operating condition.
 19. The method of claim 13 whereinthe variator has at least one roller between a first torroidal diskcoupled to an input of the automatic transmission and a second torroidaldisk coupled to an output of the automatic transmission, and thevariator has an endload fluid passageway defining therein an endloadpressure corresponding to a pressure load on the first and secondtorroidal disks required to keep the first and second torroidal disksfrom slipping, the method further comprising supplying a fixed pressurefluid to the endload fluid passageway during the at least one predefinedoperating condition.
 20. The method of claim 13 wherein the variator hasat least one roller between a first torroidal disk coupled to an inputof the automatic transmission and a second torroidal disk coupled to anoutput of the automatic transmission, and the variator has an endloadfluid passageway defining therein an endload pressure corresponding to apressure load on the first and second torroidal disks required to keepthe first and second torroidal disks from slipping, the method furthercomprising fluidly coupling the endload fluid passageway to a variablepressure fluid passageway of the variator during the operatingconditions other than the at least one predefined operating conditionsuch that fluid pressure in the endload fluid passageway is variablycontrolled by the variator during the operating conditions other thanthe at least one predefined operating condition.